Write elements of hard disk drives (HDD) must write with sufficient current to overwrite old data that already exists in the data tracks to be written. The magnitude of a write element's overwriting is usually expressed in terms of negative decibels, with a larger absolute value representing more powerful overwriting and a smaller absolute value indicating less powerful overwriting.
As understood herein, it is not sufficient simply to maximize the write current sent to a write element, because too much write current can result in write flux spilling over onto adjacent tracks, potentially changing the data in those tracks. As further understood herein, this problem grows worse when laminated disk platters are used. In laminated disk platters, a film of material that can be magnetically written and read is adhered to a substrate. In such disks, the write element's recorded pattern may be relatively wide, so that if too much write current is applied, the flux can even more easily extend into adjacent tracks (referred to as “adjacent track interference”) and also cause so-called “double-sided squeeze”, wherein a track between two tracks being written is unintentionally exposed to write flux from the tracks that straddle it.
As critically recognized by the present invention, the proper amount of write current to be applied to a write element may vary from head to head in a HDD, and for any particular head, may vary from sector to sector in the HDD. With the above recognition in mind, the present invention has been provided.